When infected by parasitic maggots of the scuttle fly, the bees apparently desert their hives at night and cluster near outdoor lights, wandering in increasingly erratic circles on the ground before dying.

The parasite could be controlling the honeybees and making them abandon their hives—or perhaps the infected bees are "committing altruistic suicide" to protect their hive mates, said entomologist John Hafernik of San Francisco State University.

Hafernik accidentally discovered the zombie bees last year while searching for dead bugs to feed lab insects. After collecting a handful of bees under a campus streetlight, he noticed maggots emerging from the corpses.

Now Hafernik and colleagues are gluing tiny radiofrequency identification tags—each no bigger than a piece of glitter—onto about 500 infected honeybees. The bees come and go from their hive through a small tube fitted with laser scanners, which register when the insects leave, and whether or not they return.

The researchers hope to find out whether the infected bees abandon the hive exclusively at night, a time when bees don't normally fly outside. If so, it could be a clue that the parasites are mind-controlling their victims.